Asteroids Near-Earth Asteroids (NEAs) Transport from the Main belt to the near-Earth region Asteroid families as a source of NEAs Linking NEAs with their origins Conclusions and Future Perspective Linking NEAs to their main-belt source regions Bojan Novakovi´c Department of Astronomy, University of Belgrade Stardust ITN: Opening Training School 21st November 2013, Glasgow, Scotland Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Near-Earth Asteroids (NEAs) Transport from the Main belt to the near-Earth region Asteroid families as a source of NEAs Linking NEAs with their origins Conclusions and Future Perspective Table of contents 1 Asteroids Main phases during the formation of the Solar system Remnants from the solar system formation Composition and taxonomic classification Where are they located? Asteroid dynamics: regular vs chaotic motion 2 Near-Earth Asteroids (NEAs) Orbital classification Dynamical lifetime 3 Transport from the Main belt to the near-Earth region Source regions and transport mechanisms of NEAs 4 Asteroid families as a source of NEAs 5 Linking NEAs with their origins Methodology Some recent results 6 Conclusions and Future Perspective Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Formation of the Solar system: some basic facts The Solar Nebula Hypothesis: basis of modern theory of planet formation Main steps: A rotating cloud of gas contracts, flattens and becomes warmer near its center ... A thin disk of dust and gas is made around the forming Sun at the center ... This disk gives birth to the Sun, planets, moons ... BUT, also to asteroids and comets. Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Asteroids: remnants from the Solar system formation Dust particles interact, sticking together to form larger and larger particles, i.e. planetesimals As planetesimals grow in size, their gravity attracts more gas and dust The collision between the planetesimals made even larger bodies, and eventually planets But some planetesimals were never incorporated into the planets Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Leftover planetesimals from planet formation Asteroids are planetesimals from the inner solar system, inside the frost line Comets are planetesimals from the outer solar system, beyond the frost line. But, even the asteroids vary widely in composition Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Spectra of an asteroid Albedo is the fraction of light that is reflected by a surface of an object. The sunlight reflected from the surfaces of asteroids, can be used to study composition of their surfaces. By determining which wavelengths of the spectrum were absorbed, and how strongly each band was absorbed relative to other bands, we can get an indication of what mixture of materials are on the asteroid's surface. Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Spectra of an asteroid Several classification schemes exists: Tholen classification SMASS classification Bus-DeMeo classification (an extension of the SMASS taxonomy into the near-IR) Main complexes are: C - dark carbonaceous objects; typical albedo 4 − 8% S - silicaceous (stony) objects; typical albedo 15 − 25% X - almost all other Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Distribution of spectral classes in the main-belt Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Orbital elements semi-major axis: a eccentricity: e inclination: i longitude of ascending node: Ω argument of perihelion: ! Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Small bodies: just about everywhere in the Solar System Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Gravitational phenomena: resonances A resonance is a gravitational phenomenon that implies commensurability between two or more frequencies of the motion of the bodies that are orbiting around the same central body. mean motion resonances (e.g. k1n + k2nJ ≈ 0 ) secular resonances (e.g. k1g + k2gS ≈ 0; ν6 = g − g6) Kozai resonances (g = s) spin orbit resonances Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Gravitational phenomena: close encounters Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking NEAs with their origins Asteroid dynamics: regular vs chaotic motion Conclusions and Future Perspective Non-gravitational phenomena: Yarkovsky effect The Yarkovsky effect is the result of partial absorption of solar radiation at the surface of an asteroid and its anisotropic re-emission in the infrared band. Affects the orbital motion of asteroids smaller than about 30 kilometers in diameter For asteroids it scales as 1=D, where D is the bodys diameter The resulting drift speed in the semi-major axis (da=dt) depends also on several other physical and dynamical parameters, such as thermal inertia, rotational period, spin obliquity, and orbital geometry Bojan Novakovi´c Linking NEAs to their main-belt source regions Asteroids Main phases during the formation of the Solar system Near-Earth Asteroids (NEAs) Remnants from the solar system formation Transport from the Main belt to the near-Earth region Composition and taxonomic classification Asteroid families as a source of NEAs Where are they located? Linking